Rotary compressor



Oct. 18, 1960 Y. BREELLE 2,956,735

ROTARY COMPRESSOR Filed Deo. 27, 1957 2 Sheets-Sheet 1 ATTORNEYS Oct. 18, 1960 Y. BREELLE ROTARY COMPRESSOR Filed nec. 27. 1957 2 Sheets-Sheet 2 ATTORNEYS United States Patent ROTARY COMPRESSOR Yves Brelle, Rueil-Malmaison, France, assignor to Institut Franais du Petrole, des Carburants et Lubritiants, Paris, France Filed Dec. 27, 1957, Ser. No. 705,526

Claims priority, application France Dec. 28, 1956 4 Claims. (Cl. 230-150) Y This invention relates to compressors, `and more particularly to rotary compressors of the volumetric type.

It is an object of my invention to provide a compressor of better output and capable of rotating at higher speeds than the known Itypes, thereby permitting the obtaining of higher compression rates' than the latter at a given output.

. It is another object tof my invention to provide a rotary compressor of better performance at higher speeds than the known constructions, due to an improved arrangement which is preferably equilibrated to absorb the forces exerted kon the rotors and stator of the compressor, requires no lubrication, and has a simple cooling system.

Among the known compressors, there are noteworthy the blade or turbine compressors and the Roots-Connersville compressors. A compressor of the latter type is described in the Patent 2,489,887. The high temperatures occurring during the compression of a medium such as air lead to a number of undesirable effects.v Lubrication is often required and presents a difficult problem in the art of building high speed compressors. Those known compressors which operate without lubrication permit only to reach a limited rate of compression for each compression stage.

Lack of equilibration of the rotating parts may also contribute to non-uniform expansion of rotating parts and eventual binding of the latter. Moreover the known rotary compressors are not so satisfactorily as the rotary compressor according to the present invention since they do not permit to reach so high speeds'.

These drawbacks of the known constructions are avoided and the objects stated hereinbefore are attained by the rotary compressor according to my invention, which comprises as a main feature a number of rotors which may be internally cooled and which rotate without exercising friction upon each other, there being provided a sufficient distance between the rotors to avoid Such friction even at maximum elevation of speeds of the rotors at high compression rates. The necessary sealing elfect between the rotors and the walls of the cavities in which they rotate, are brought about by labyrinth-type sealing effects between the cavity walls and a groove-and-rib sealing arrangement covering the entire cooperating surfaces of the rotors.

Where this is' permissible, as at the end surface of the cylindrical rotors, similar labyrinth-typesealing grooves and ribs `of annular shapes are also provided in the walls of the cavities in which the rotors are housed.

As one important feature of the invention, the rotors of the compressor comprise a central or compression rotor bearing a number n of piston lobes, preferably distributed evenly about the periphery of the rotor at radial angles taken at the rotor shaft of relative to each other. The compressor further comprises n- Dcr be fulfilled, in which e and n have been explained hereinbefore; Dgr is the diameter of the gate rotor, and Dcr is the diameter of the central or compression rotor.

While the compression is effected in the internal chambers or cavities of the compressor stator, synchronism of the movement of the rotors is achieved by a gear train, the gears of which are mounted on the shafts of the various rotors, outside the compression space, in a separatey gear box or gear space in the compressor. Y The preferably cylindrical contact surfaces of the rotors are covered by an arrangement of preferably longitudinally, i.e., axially extending ribs and grooves, the ribs of one rotor protruding, during the rotation of both in opposite sense, in the grooves of the other, andvice versa, without effecting direct mechanical contact even at the highest speeds, but creating between the grooves and ribs a turbulence which causes the gases passing therethrough to lose the most of their velocity, thus representing a labyrinth effect which permits a perfect sealing. without any bodily friction between the rotors, or even between a rotor thus provided with a rib-and-groove surface and the smooth walls of the stator bore housing the At the same time, each of the rotors as well as the stator of the rotary compressor, are designed as hollow bodies and permit an optimum cooling in a much simpler. manner than in the known compressors having solid rotor bodies. v

The central rotor as well as the gate rotor or rotors rotate in chambers or cavities of preferably cylindrical form provided by bores in the engine stator, or cylinder block. The cavities housing the gate rotors have about the same diameter as the rotors therein, permitting a little play between the ribs of the latter and the internal wall of the cavity. The central rotor rotates in a coaxially cylindrical central chamber having a cross-sectional diameter which is about equal to that of the central rotor plus twice the height of a piston lobe, a little playl being., left between the ribbed ridges of the piston lobes andthe internal wall of the central chamber.

Various suitable embodiments of the shape of the pistons and wells therefor, the placement of the rotors relative to each other, and the cooling system, have been vdescribed in my co-pending applications Serial No. 688,- 908, tiled on October 10, 1957 now U.S. Patent 2,920,610, granted January 12, 1960, Serial No. 696,538, tiled on November 14, 1957, U.S. Patent 2,870,752, granted Ian` uary 27, 1959, and Serial No. 698,291, filed on November 22, 1957, and now U.S. Patent 2,927,560, granted March 8, 1960. t Preferably, the wells of the gate rotors according to this invention will be given the shape described in patent application 688,908, tiled on October 10, 1957, now U.S. Patent 2,920,610. f

`I thus avoid compression in a well and subsequent loss of the compressed portion Iby causing the gas enclosed in the space in front of the leading edge of the piston penetrating into the well to recycle back into the compression zone. I also avoid the useless compression .and heating of the material of well and piston caused inthe known constructions.

This well shape also permits evacuation of the residual: enclosed gases in front of the leading slope of tlie'pistons of the central rotor between the latter and the wall of the corresponding well, whereupon these gases under partial pressure can be recirculated into the compression compartment of the central chamber.

In a simplest embodiment of the invention which comprises in the rotary compressor a central -rotor bearing two pistons and one gate rotor, in which arrangement one piston suctions gaseous uid to -be compressed into the central stator chamber and the other piston cornpresses the previously introduced fluid portion, the single gate rotor serves not only as a sealing rotor between the intake and the compression compartments of the central chamber, but also at the same time as a distributing means for the compressed fluid.

High compression rates in the order of 50 atmospheres and more can be achieved by another preferred embodiment of the rotary compressor which comprises at least two compression stages, and wherein the compressed uid from the first stage is fed into the intake of the next following stage for further compression therein, from there eventually to a third stage, and so on.

The outputs of several compression systems comprising a single common central rotor bearing several pistous and each cooperating with a different one of several intake and discharge ports and a corresponding number of gate rotors which are mounted in a common stator, can be combined by uniting the discharge conduits of the several systems in a common manifold leading to a storage Vessel or pressure reservoir.

Such a combined system has a higher output than the single intake systems, but does not permit attainment of the high pressures of the latter due to the fact that the compression compartment of each piston on the single central rotor is shorter than when the pistons of the central rotor all cooperate only with the same single intake port and discharge port.

However, the aforesaid combined system comprising a Single common rotor bearing several pistons, each of which cooperates with a gate rotor in a different compression system, in the same compressor stator, offers the advantage that, by a corresponding arrangement of compression compartments of different lengths, fluid portions of different predetermined pressures can be simultaneously produced by the same compressor.

Normally, the intake as well as the discharge ports have their orices in the cylindrical internal wall of the central chamber and/or the cavities housing the rotors. It can, however, be of advantage to provide the orifice or orifices for the discharge conduits in the internal end surfaces of each of the cavities housing a gate rotor, i.e., the wall thereof transverse to the rotor shaft; in this case each discharge orifice is so disposed in the cavity end Wall that it is in free communication with one of the wells in the corresponding gate rotor when the latter communicates simultaneously with the compression compaxtment `of the central chamber, until shortly prior to the instant that the piston of the central rotor reaches its maximum penetration in the well-communication. Thereby, it is avoided that compressed fluid is reintroduced into the well due to a suction effect due to the increasing free volume in the well as the piston recedes therefrom. In this specific arrangement of the discharge orifice, it is recommendable to use pistons and wells of a shape described in my patent application Serial No. 688,908, supra.

The rotary compressor according to this invention is not limited to the embodiments hereinafter described in detail in connection with the accompanying drawings, but may also comprise central rotors having more than two pistons and a corresponding number of gate rotors, each of which has at least two wells.

In the drawings:

Figure 1 is a transverse sectional view of an embodiment of a single-stage rotary compressor according to the invention;

Figure la is a partial sectional view of a somewhat different construction of the discharge means shown in Figure l;

Figure 2 is a longitudinal sectional view of a two-stage rotary compressor according to the invention;

Figure 3 is a transverse sectional View of another embodiment of a rotary compressor of the single stage type shown in Figure l, but comprising two compression systems combined in the same compressor;

Figure 4 is a transverse sectional view of still another embodiment of a rotary compressor similar to that shown in Figure 3; and

Figure 5 shows in transverse sectional view a rotary compressor similar to that shown in Figure 4 but combined as a two-stage compressor.

Referring now to the drawings in detail, and in particular to Figure l, reference numeral 1 designates the casing or cylinder block being the stator of the rotary compressor according to this invention.

The stator 1 comprises an outer wall 2 and inner walls 3, intermediate which inner and outer walls there are enclosed cooling spaces 4.

Walls 3 enclose a central, preferably cylindrical bore or central chamber 5, in which there is housed a central or compression rotor 6 mounted on a shaft 7 for rotation therewith. Rotor 6 bears two piston lobes 8 and 9, protruding diametrically opposite each other from the peripheral wall 10 of the rotor, which wall is covered by a plurality of ribs and grooves extending in axial direction. The ridges 8a and 9a of the pistons 8 and 9 also bear ribs and grooves, thus achieving a labyrinthtype sealing effect at the wall of central chamber 5. The diameter of central chamber 5 is very slightly greater than the diameter of rotor 6 plus twice the height of the piston, so as to leave a little play between ridges 8a and 9a of the piston and the internal wall of chamber 5.

A second chamber or cavity 11, which is also enclosed by inner walls 3, opens peripherally into the central chamber 5. This cavity 11 houses a gate rotor 12 which is mounted for rotation with shaft 13. This shaft 13 is disposed parallel with shaft 7 of the central rotor 6. The preferably cylindrical peripheral surface `14 of rotor 12 is also covered with longitudinal grooves and ribs, which intermesh, Ifree from friction, with the ribs and grooves of surface 10 of rotor 6, along the line of con- .tact between the two rotors.

Rotor 12 is further provided with two diametrically opposed wells 15 and 16 for the passage of pistons 8 and 9 therethrough.

The compressor casing 1 `further comprises an intake port 17 Ileading from the outside to the region where chamber 5 and cavity 11 merge, and having an orice 18 in ythat region for the admission of a gaseous fluid to be compressed in the chamber 5.

A discharge conduit 19 leads from an orifice 20 in the peripheral wall of cavity 11 through the stator 1 to an outlet opening 21.

A safety valve 22 may be provided in the outer stator wall 2 which communicates with the discharge conduit y19 and can be pretensioned by suitable means, such as spring 23, so as to open when the pressure in the compressor reaches a determined safety limit.

In a modified embodiment illustrated partially in Figure la, discharge conduit 19 opens into the cavity 11 of `the stator 1 ythrough an orifice 20 in one of the lateral end walls of cavity 11.

Stator 1 further comprises openings 24 in the outer wall 2 `to permit passage of coolant therethrough into cooling spaces 4.

The pistons 8 and 9 and the aforesaid contact line between rotors `6 .and 12 subdivide the space between lrotor 6 and the inner wall of chamber 5 into a number of compartments 5a, 5b and Sc, and, in the position shown in Figure l, compartment 5a may be called the essaies admission compartment and 5c the compression compartment.

The compressor is driven from a motor (not shown) which engages the central rotor shaft 7, for instance, via a gear transmission (not shown). The gate rotor shaft 13 is rotated synchronizedly with shaft 7, in opposite sense of rotation, via Igears 25 and 26 in :a separate gear chamber 27 of stator 1.

Assuming that the central rotor 6 rotates in clockwise direction, its piston 9 will suction a compressible gaseous flu-id through intake port 17 into compartment 5a of central chamber 5. As rotor 6 completes its cycle, piston 8 passes through well of rotor 12 and then cuts oi communication between intake port 17 `and the central chamber 5, the fluid thus enclosed in compartment 5b between the trai-ling slope 9c and the leading slope 8b of the pistons 9 and 8, respectively, being transported through the central chamber 5 until piston 9 passes through well 16 of rotor 12. Thereafter, the yfluid portion is compressed in compartment 5c between the leading slope 8b of piston b and the walls of rotors 6 and 12 (in the position shown in Figure l), until well 15 of rotor 12 establishes free communication between compartment 5c and discharge opening 20 (or 20 in Figure la). The compressed fluid is then expelled therethrough until piston 8, penetrating into well 15, closes off the opening 20.

This working cycle is in the meantime repeated by piston 9, there thus being two full compression cycles for each revolution of the central rotor 6.

Figure 2 illustrates a two-stage compressor in Which the cross-sectional arrangement of the rotors is similar Ito that shown in Figure l, wherefore identical parts in both gures bear the same reference numerals.

It will be noted that the end faces 6a and 6b and 12a and 12b of rotors 6 `and 12 :are provided with a sealing system of annular ribs and grooves which mesh, free from friction, with a corresponding system of grooves and ribs in the inner end surface 11a, 11b of `cavity 111 and 5d, 5e of central chamber 5.

The secondary compression stage comprises a central or compression rotor 30 mounted on shaft 7, and a ygate rotor 33 mounted on shaft 13. Rotor 30r bears diametrically opposed pistons 31 and 32, which, as will be noted, are disposed in a plane at right :angles to .the plane of pistons 8 and 9 of rotor 6.

Rotor 33 is provided with wells 34 and 35. Sealing systems similar to those of rotors 6 and 12 are also provided on the peripheral and the lateral end surfaces of rotors 30 and 33, for instance at 31a, 30a, 30h, and 33a and 33b, comprising grooves and ribs also in the end walls, transverse .to the shafts 7 and 13, of central c-hamber 36 and 37 in .the stator 1 housing rotors 30 and 33, respectively.

:From discharge orifice of the primary compression stage, :a conduit 3S leads through the interior or preferably, for better cooling, externally of the stator to the intake port 39 of the second compression stage. The right portion of this conduit 39 as well as the orifice 20 are shown by phantom lines -to indicate that these parts lie in front of the plane of Figure 2, while dashed lines of the left portion conduit 38 and the orice 39l small gas portions escaping from the central chambers penetrate to the rotary bearings 42.

Each stage of the compressor illustrated in Figure 2 functions in a similar manner as described in Figure 1, the compressed ii-uid from orifice 2i) being transferred through conduit 38 through orifice 39 linto the secondaryy compression system, lwhere the compression rate of Ithe fluid can be further increased whereupon the fluid thus compressed for a second time is discharged through orice 40.

Figure 3 illustrates another embodiment of a rotary compressor according to the invention which comprises the casing 50 having outer and inner walls 51 and 5-2, respectively, enclosing cooling space 53 therebetween.

Inner walls 52 enclose a central chamber 54 and two lateral cavities 55 and 56, each of spaces 54, 55 and 56 being of substantially cylindrical shape, the central cylinder axes of all three spaces being disposed in parallel and in the same plane.

Central chamber 54 houses a central rotor 60 mounted on a shaft 61 for rotation therewith, which shaft 61 is the power shaft of the engine. Rotor 60 bears on its outer surface 62, a sealing system of grooves and ribs and, diametrically opposite each other, two piston lobes 63 and 64, the ridges 63a and 64a of which are also provided withl the same kind of labyrinth-type sealing means.

Stator cavity 55 houses a gate rotor 70 which is mounted on a shaft 71 parallel with shaft 61 and which rotor is provided with -two wells 72 and 73 diametrically opposite each other.

The peripheral surface of the preferably cylindershaped rotor 70 is covered with labyrinthatype sealing means comprising grooves and ribs 74 which intermesh, without, however, effecting mechanical contact and therefore free from friction, with corresponding ribs and' grooves on surface 62 of rotor 60.

Diametrically opposite rotor 70, another gate rotor 8d) is mounted on a shaft 81, which shaft is parallel to and in the same plane as rotor shafts 61 and 71. This rotor is provided with wells 82 and 83, and with sealing means 84 similar to those of rotor 60.

Compressible gaseous fluids are introduced into the central chamber 54 through intake port 65 on the one hand, next adjacent cavity 55, and through intake port 66, on the other hand, next adjacent cavity 56.

Compressed fluids are discharged from the stator through dis-charge ports 67 and 68.

These two discharge ports may be connected by la manifold 69 to combine the two compressed fluid portions, if this is desirable.

A safety valve 75 is pro-vided in the stator and communicates with discharge port 67.

After pistons 63 and 64 have suctioned in, during their clockwise rotations, compressible fluid portions through intake ports 66 and 65, respectively, each succeeding priston that cuts off communication with the corresponding intake port compresses the fluid portion forward of its leading slope and the Wall of the gate rotor toward which it moves, until a well in that gate rotor establishes com' munication between the respective compression compartment 54a or 54b in the central chamber 54, and the respective discharge conduit 68 and 67, respectively.

These two compression zones in compartments 54a and 54b signify that this embodiment combines, in a manner of speaking, two compressor units in one stator. Since the compression compartments 54a and 5411 are of the same volume at the same instant, and the volumes of compressible fluid taken in are also the same, the pressures obtained in discharge conduits 67 and 68 will also be the same, if the admitted fluids are also of the same initial pressure, for instance that of the surrounding atmosphere.

In the embodiment of a rotary compressor according to the invention shown in Figure 4, parts identical with those shown in Figure 3 bear like numerals. A basic difference resides in the fact that while rotor shafts 61, 71 and 81 are all parallel with each other, shafts 71 and I61 extend in one plane, and shafts 81 and 61 in another plane at an angle a with the former plane taken at shaft 61.

Consequently, the intake-and-compression compartments of the central chamber 54 are of different exten-vM sion, compartment 54e, for instance, being larger than compartment 54d. rIhis permits obtaining at discharge ports 67 and 68 different compression rates and different outputs of compressed uids.

It is, `therefore, advisable to provide for separate safety valve means for each discharge conduit, conduit 68 also being provided with a safety valve 76.

Finally, Figure illustrates an embodiment of a rotary compressor according to the invention similar to that shown in Figure 4, like parts in both figures being designated by like numerals.

However, in the embodiment shown in Figure 5, the discharge conduit of gate rotor 30 is replaced by a connecting channel 85 for transferring the compressed fluid from the compartment 54d of smaller output of lthe central chamber 54 to Ithe cavity 55 housing rotor 7G, and opening thereinto intermediate the intake port 65 and the discharge port 67 through orifice 86 having the diameter P-q- Each of wells 72 and 73 of gate rotor 70 then passes this orifice 86 and is filled with pre-compressed fiuid from well y32 or 83 via channel 85 before establishing communication between the large-output compartment 54e and discharge conduit 67.

Thereby is avoided the filling of well 72 (or 73) with compressed gases from the reservoir freely communicating with the discharge port 67 containing iiuid under high pressure, which would otherwise result in a decrease of the compression rate in said reservoir due to the fact that gases introduced into said wells would assume atmospheric pressure from intake 65.

The rotary compressors according to the invention may also be used as vacuum pumps, in which case the evacuation orifice will preferably open into the compression compartment or compartments of the central chamber of the engine.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions, and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

What is claimed is:

1. A rotary compressor for the compression of gaseous uids, comprising, a stator having fluid inlet means and iiuid outlet means, a central chamber in said stator, a central rotor having a body portion with a substantially cylindrical surface, at least two rotary pistons disposed on said peripheral surface of said central rotor, said central rotor and pistons thereon being disposed for rotation in said central chamber, a plurality of cavities in said stator peripheral to said central chamber and having a cylindrical portion, a plurality of gate rotors having at least two wells in the rotor surfaces peripherally disposed therein for the passage of said pistons of said central rotor, the axes of said central rotor and said gate rotors being parallel with each other, each of said gate rotors being disposed in one of said cavities for rotation therein, cach portion of the annular space defined by the body portion of said central rotor, the wall of said central chamber and two gate rotors disposed adjacent each other about said central rotor communicating directly and constantly with said fluid inlet means and communieating with said fluid outlet means via one of said wells of one of said gate rotors, said iiuid outlet means opening into a first of said cavities, said stator having channel means connecting said first cavity with a second one of said cavities so that compressed gaseous fluid is expelled from said annular space to said channel means via wells of the gate rotor disposed into said second cavity and is delivered by said channel means to the wells of the gate rotor disposed into said first cavity through an outlet port of said channel means opening in the latter cavity at such a distance from said outlet port that each of the wells of the gate rotor disposed in said first cavity communicates with said channel means prior to entering into communication with the fluid outlet means, and opening into said fluid outlet means only after interrupting communication lwith said channel means thereby substantially avoiding any suction of gases from the reservoir containing fluid under high pressure, freely communicating with, said outlet port, in the wells of the gate rotor disposed into that cavity provided with said outlet port.

2. A rotary compressor for the compression of gaseous fluid as described in claim 1, and having separate uid outlets freely communicating with an external reservoir, the compression process in one of said compartments allowing to obtain successively in each of said wells of that one of said gate rotors cooperating with that one of said fluid outlets associated with another compartment prior to entering into communication with said last mentioned fluid outlet, a presure substantially equal to the pressure attained by the compressed gases at said lastmentioned iiuid outlet.

3. A rotary compressor for the compression of gaseous fluid in several stages comprising, a stator having a plurality of inlet ports and one outlet port freely communieating with a reservoir for compressed gaseous fiuid, a central chamber in said stator, a central rotor having one peripheral substantially cylindrical surface, at least two rotary pistons disposed on said peripheral surface of said central rotor, said central rotor and pistons thereon being disposed for rotation in said central chamber, the space between the wall of said central chamber and the cylindrical surface of said central rotor constituting an annular chamber, one pair of cavities in said stator peripheral to said central chamber, said stator comprising channel means interconnecting one cavity of said pair with the other cavity, a first and a second gate rotor subdividing r said annular chamber into at least two compartments,

each gate rotor having at least two wells in the rotor surface peripherally disposed therein for the passage of said pistons of said central rotor, the axes of said central rotor and said gate rotors being parallel with each other, said gate rotors being disposed each in one of said cavities for rotation therein, in such a manner that compressed uid is transferred from one of said compartments via a well of the first gate rotor to said channel means intermittently whenever said well of said iirst gate rotor registers with said compartment and said channel means, and from said channel means via a well of the second gate rotor to one of said outlet parts only intermittently as the wells of said second gate rotor register first with said channel means and then with said outlet port, thereby preventing any substantial discharge of compressed gaseous iiuid from said reservoir in the wells of said second gate rotor.

4. A rotary compressor for the compression of gaseous uid in several stages comprising, a stator having a central chamber, a central rotor having one peripheral substantially cylindrical surface, at least two pistons protruding from said peripheral surface of said central rotor, said central rotor and pistons thereon being disposed in said central chamber for rotation therein, the annular space between said central chamber and said cylindrical surface of said central rotor being provided with a plurality of inlet ports, at least one pair of cavities in said stator peripheral to said central chamber, one outlet port opening into a first cavity of said pair, at least one pair of gate rotors, each having at least two wells in the rotor surface peripherally disposed therein for the passage of said pistons of said central rotor, the axes of said central rotor and said gate rotors being parallel with each other, said gate rotors being disposed each in one of said cavities for rotation therein and subdividing said annular space into two first and second compartments, said stator having internal channel means for connecting the two cavities of said pair with each other, said channel means opening with the one end thereof into a second cavity of .said pair at a distance from the intersection of that cavity with the central chamber which is shorter than the peripheral width of a well in the gate rotor rotating in said cavity so that communication between said end of said channel means and said iirst compartment of said annular space may be established by means of the wells of said gate rotor, said channel means opening with the other end thereof into the first cavity of said pair at a distance from said first compartment and from any inlet port opening into the latter which distance is greater than the peripheral width of a well in the first gate rotor rotating in said rst cavity so that compressed gaseous fluid delivered by said channel means to the wells of said rst gate rotor can not escape through an inlet port and is discharged through the outlet port when, after rotation of said iirst gate rotor, a well of the latter communicates with said outlet port, the peripheral width of the gate rotors in both aforesaid cases being taken in a plane transverse yto the axis of said gate rotor; and a gear drive outside said central chamber and cavities for driving said rotors in synchronized rotation.

References Cited in the tile of this patent UNITED STATES PATENTS Disston July 20, 1875 Phinney et al. Apr. 22, 1879 Madero May 21, 1918 Green Oct. 1, 1929 Whiteld Sept. 13, 1938 Whiteld Nov. 21, 1939 Whitfield Nov. 21, 1939 Brown Oct. 5, 1954 Erickson Ian. 11, 1955 Fawzi ..-.f. Oct. 14, 1958 Breelle Jan. 27, 1959 FOREIGN PATENTS Germany Aug. 26, 1915 'France Oct. l2, 1918 France Sept. 27, 1937 Germany Feb. 12, 1953 France Nov. 12, 1957 

